Allow enableMultisite blueprint step

[bcotrim]

Related issues

• Fixes STU-831

Proposed Changes

Allow enableMultisite blueprint step

• Remove enableMultisite from the unsupported blueprint features list, allowing blueprints to configure WordPress multisite

Bump @wp-playground packages to 3.0.54

• Includes upstream fix for $_SERVER['HTTP_HOST'] handling in multisite, which fixes site restart failures

Add multisite validation (CLI + Desktop)

CLI: Error early when a blueprint contains enableMultisite but no --domain flag is provided. Multisite doesn't support custom ports, so a custom domain is required.

Desktop app: When a blueprint with enableMultisite is detected:

• Auto-enable the custom domain field and show advanced settings
• Lock the custom domain toggle so users can't disable it
• Show an info notice: "WordPress multisite requires a custom domain."

Shared utility

• Add blueprintHasMultisite() helper in common/lib/blueprint-settings.ts, used by both CLI and desktop

Testing Instructions

CLI

1. Create a blueprint JSON with an enableMultisite step
2. Run npm run cli:build && node dist/cli/main.js site create ~/test-multisite --blueprint /tmp/multisite.json
3. Verify it errors with a message about requiring --domain
4. Run again with --domain test.local — should proceed normally

Desktop

1. Open Studio, go to Add Site
2. Use a blueprint URL containing enableMultisite (e.g., via deeplink)
3. Verify advanced settings auto-open, custom domain is enabled and locked
4. Verify the info notice about multisite requiring a custom domain is shown

Tests

npm test -- common/lib/tests/blueprint-settings.test.ts cli/commands/site/tests/create.test.ts

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?